Write comprehensive configuration documentation

[grayside]

There's getting to be too much to just dump it into the middle of the README. The current example/Gruntconfig.json is trying to be a template for a minimal implementation, it doesn't explain the configuration it's using, nor does it include a lot of what I would consider "standard" for our projects.

[grayside]

As part of this, we may want to standardize the configuration keys used in the Gruntconfig. Some of them are informed by the underlying grunt plugins, which is good if you know the plugin but confusing if you are trying to come in with fresh grunt eyes on this project. If so, backwards compatibility.

[arithmetric]

@grayside Check out this start in the docs/config branch: https://github.com/phase2/grunt-drupal-tasks/blob/docs/config/CONFIG.md

Do you have any suggestions on the format? Does it make sense to organize it by task?

[grayside]

I was thinking we'd start with a brief blurb explaining that this project is largely about configuring the contrib plugins, so your project is about configuring the grunt-drupal-tasks. Second, an inline example of the minimum viable configuration, where everything you see is functional. That's a bit less than the current example/Gruntconfig.json. From there, I thought go task-by-task (e.g., validate) explaining the options with inline code blocks.

Formatting-wise, not sure if each option should be a header, or more like a bold intro section on a list bullet. Probably depends on how much we have to say.

Per what I was saying about normalizing the configuration, we may want to think whether more of the configuration should be task-driven. E.g., should phpcs be a top-level config key, or should it be validate.phpcs? There are a couple awkward cross-over cases, (see #19) but it may be a bit more clear if we are trying to emphasize operations and goals over the individual steps.

[arithmetric]

@grayside I merged a refresh for the documentation along the lines we discussed. Could you review and see if it satisfies these needs?